I believe it is an acronym for "Fresh Off the Boat", i.e. an immigrant. It's a slang term and I personally don't use it too much but have heard it used fairly often.

I'd argue that the modern definition has nothing to do with immigrant status, and is entirely about whether or not you can pass as a native English speaker. It just so happens that most people who have accents are immigrants, and you can reasonably assume that anyone who didn't grow up speaking English as a native language is going to have an accent.

You are not a fob if you moved here from China at 9 years old, didn't read or speak your first word of English until then, and have no discernible accent as an adult.

No one would call a Hong Konger with a HK English accent a fob either.

> you can pass as a native English speaker

Also clothing :-)